CN1574425A - Anode compostition for lithium battery, and anode and lithium battery using the same - Google Patents

Abstract

Provided are an anode composition for a lithium battery, and an anode and a lithium battery using the anode composition. The anode composition can improve the characteristics of the anode and battery while using water which is harmless to the human body as a solvent. The anode composition includes an anode active material, a synthetic rubber binder, a cellulose-based dispersant, and a water-soluble anionic polyelectrolyte.

Description

Anode composition for lithium battery, anode and lithium battery using the same

Background of the invention

This application claims the benefit of Korean Patent Application No. 2003-40085 filed with the Korean Intellectual Property Office on Jun. 20, 2003, which is hereby incorporated by reference.

field of invention

In general, the present invention relates to lithium batteries. More particularly, the present invention relates to an anode composition for a lithium battery capable of improving anode characteristics and battery characteristics while using water as a solvent, and also to an anode and a lithium battery using the composition.

Description of related technologies

In recent years, as portable electronic devices such as personal data assistants (PDAs), portable phones and notebook computers have been widely used in various fields, the batteries that drive these electronic devices have become smaller, thinner, lighter and better quality .

Due to advantages such as light weight and high energy density, lithium batteries are used as the main driving source of many portable electronic devices. Like all batteries, lithium batteries have an anode and a cathode, both of which are composed of electroactive materials. An active material for forming a cathode (hereinafter referred to as a cathode active material) may be a lithium-containing transition metal oxide such as LiCoO ₂ and LiNiO ₂ or a chalcogenide such as MoS ₂ . Due to their layered crystal structure, these compounds allow the reversible intercalation or deintercalation of lithium ions, and thus are widely used as cathode active materials for lithium batteries.

An active material used as an anode of a lithium battery (hereinafter referred to as an anode active material) is lithium metal. However, when lithium metal is intercalated and extracted during lithium battery charge/discharge cycles, sometimes needle-like lithium dendrites are repeatedly deposited on the anode surface. These needle-like lithium dendrites not only reduce the charging/discharging efficiency of the battery, but can also come into contact with the cathode, causing an internal short circuit.

Considering these problems, alternative anode active materials have been suggested. Examples are: lithium alloys that allow reversible intercalation/extraction of lithium, metal powders, carbonaceous materials such as graphite, metal oxides, or metal sulfides. However, when charge/discharge cycles are repeated in a lithium battery using a lithium alloy plate as an anode, current collection efficiency decreases due to pulverization of the alloy plate, thereby deteriorating charge/discharge cycle characteristics of the battery.

Due to these disadvantages, the anode plate cannot be made only from metal powders, carbonaceous materials, metal oxides or metal sulphides. Therefore, a binder is usually added. For example, viable anodes are made from mixtures of carbon-containing anode active materials and elastic, rubber-based polymer binders.

When metal oxides or metal sulfides are used as the base anode active material, in addition to the binder, a conductive material may be used to enhance charge/discharge characteristics of the battery. Generally, the carbonaceous material used for the anode is ground into powder and mixed with a binder to make the anode plate. Then, a rubber-based polymer was used as a binder to wrap the carbonaceous material particles, but this made lithium ion intercalation and deintercalation reactions difficult. As a result, the high-efficiency discharge characteristics of lithium batteries are significantly reduced.

Another disadvantage is that, irrespective of the type and shape of the carbonaceous material used, the use of conventional binders without other additives results in poor adhesion between the carbonaceous material and the metal substrate made of metal. To compensate, a large amount of adhesive is required. Carbonaceous materials can be covered with a binder, but this reduces the efficient discharge characteristics of the battery. On the other hand, if a small amount of binder is used in order to maintain discharge characteristics, the anode active material layer may be separated from the substrate. However, this configuration makes it difficult to form an anode plate and increases the possibility of forming a poor anode plate. In this regard, attention has focused on finding an alternative method to increase the adhesion of carbon-containing anode active materials to the substrate while avoiding the excessive use of binders in lithium batteries. A previously attempted solution discloses a hybrid binder for an anode comprising polyamic acid and at least one polymer selected from polyamide resins, polyvinylpyrrolidone and hydroxyalkyl cellulose for Ensure a long life cycle and enhance security.

However, since the polyamic acid used for mixing the binder must be removed at a heat treatment temperature of 200-400°C during drying of the anode plate, the production method is complicated and the physical properties of the anode may change during the production process. . Thus, hybrid binders of polyvinylpyrrolidone and styrene butadiene rubber (SBR) have been suggested as alternative binder materials for anodes. However, the use of this hybrid binder can reduce the uniformity of the anode due to the difference in the strength of its adhesion between the two materials and lead to separation of the anode active material or loosening of the solid components during charge/discharge cycles.

In addition, the production of binders for anode compositions generally requires organic solvents such as N-methyl-2-pyrrolidone (NMP), which is harmful to humans. Therefore, problems arise due to the complexity of the anode production method, which requires multi-step processes and equipment, and environmental pollution due to the discharge of pollutants such as organic solvents. In order to solve the above problems, a method of preparing an aqueous anode active material suspension containing water as a solvent and a water-soluble SBR binder has been proposed. However, one disadvantage of this method is that the use of only SBR-based adhesives in small quantities leads to the above-mentioned reduction in adhesion and anode characteristics, because of the point-contact adhesion properties of SBR and the small contact area with the active material leading to SBR adhesion. The adhesive force of the agent is weak. As a result, using only the SBR binder may cause separation of the active material from the electrode plate or decrease the adhesion between the active materials. Thus, using only the SBR binder degrades the charge/discharge cycle characteristics of the lithium battery.

Summary of the invention

The invention provides an aqueous anode composition for lithium batteries. The aqueous anode compositions of the present invention are environmentally friendly and provide improved suspension dispersibility, as well as improved adhesion between one or more anode active materials and the anode plate. In addition, the present invention provides an anode made of the anode composition. The invention also provides a lithium battery using an anode made from the aqueous anode composition of the invention.

Brief introduction to the drawings

1 illustrates low-temperature discharge capacity characteristics of lithium secondary batteries using the anodes manufactured according to Example 1 and Comparative Example 1. FIG.

FIG. 2 illustrates life cycle characteristics of lithium secondary batteries using anodes manufactured according to Examples 1-3 and Comparative Examples 1 and 2. FIG.

Detailed description of the invention

Provided is a lithium battery with improved anode characteristics and battery performance, particularly high energy density and excellent low-temperature capacity characteristics and cycle characteristics. For example, in one embodiment, a water-soluble anionic polyelectrolyte is added to an aqueous anode composition using water as a solvent to increase suspension dispersibility and adhesion between the anode active material and the anode plate.

In one embodiment, a synthetic rubber binder, water, a cellulose-based dispersant, and a water-soluble anionic polyelectrolyte are mixed with an anode active material to prepare an anode composition that is used in the manufacture of a lithium battery. Since the anode composition containing the water-soluble anionic polyelectrolyte can be dispersed more effectively than conventional methods, the adhesion between the anode active material and the anode plate is enhanced and the amount of the anode active material in the anode is increased. The enhanced adhesion and increased amount of anode active material make it possible to produce lithium batteries with excellent battery characteristics.

According to one embodiment of the present invention, the anode active material as a component of the anode composition may be, but is not limited to, a carbonaceous material such as natural graphite, artificial graphite, coke or carbon fiber. Alternatively, the anode active material may be a compound containing one or more selected from Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, and Ti capable of forming a lithium-based alloy. In another embodiment, the anode active material may be a carbonaceous material and a complex containing one or more compounds selected from the group consisting of Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, and Ti . In another embodiment, the anode active material is a lithium-containing nitride.

The anode active material plays an important role in the battery performance, and in order to improve the battery performance, it should dominate in the anode composition. Herein, the anode active material is used in an amount of 90-99% by weight, based on the total amount of the anode composition. If the amount of the anode active material is less than 90% by weight, battery performance may decrease due to lack of the anode active material. On the other hand, if it exceeds 99% by weight, the dispersibility and adhesion of the anode active material may decrease.

There is no limit to the anode current collector of the lithium battery as long as it is an electrical conductor that does not undergo chemical reactions in the lithium battery. Illustratively, the anode current collector can be made of stainless steel, nickel, copper, titanium or a copper alloy. Alternatively, it can be made of copper or stainless steel coated with carbon, nickel, titanium or silver.

In one embodiment, the water-soluble anionic polyelectrolyte contained in the aqueous anode composition is a polymer containing dissociative groups in its polymer chain or a compound with properties similar to the polymer. In other words, water-soluble anionic polyelectrolytes are compounds in which the molecule becomes negatively charged when a dissociating group (such as sodium ion or hydrogen ion) dissociates in a solvent such as water. Embodiments of the present invention use water-soluble anionic polyelectrolytes to increase dispersibility through electronic repulsion between negatively charged particles in the anode composition. Examples of suitable water-soluble anionic polyelectrolytes are citric acid, citrates, tartaric acid, tartrates, succinic acid, succinates, poly(meth)acrylic acid, poly(meth)acrylates, and mixtures thereof. To increase solubility in water, the water-soluble anionic polyelectrolyte may be a sodium or ammonium salt of the above substances.

In various embodiments, the water-soluble anionic polyelectrolyte is used in an amount of about 0.1-4.0 wt%, preferably 0.2-2.0 wt%, based on the total amount of the anode composition. If the water-soluble anionic polyelectrolyte is used in an amount of less than about 0.1% by weight, a sufficient effect of addition cannot be obtained. On the other hand, if it exceeds about 4% by weight, the viscosity increases and the dispersibility cannot be further increased, which is not suitable for preparing anode active material suspension.

The synthetic rubber binder contained in the anode composition of the lithium battery of the present invention can be, for example, styrene butadiene rubber, nitrile butadiene rubber, (meth)methyl acrylate butadiene rubber, chloroprene Rubber, carboxy-modified styrene butadiene rubber, modified polyorganosiloxane polymer, or mixtures thereof.

A synthetic rubber binder mixed with a water-soluble anionic polyelectrolyte reduces anode active material delamination and internal short circuits due to poor adhesion of the anode active material. Thereby, the charge/discharge cycle characteristics of the lithium battery are enhanced. In addition, due to the good dispersibility of the aqueous anode composition, the amount of anode active material increases, which makes it possible to produce lithium batteries with high energy density and good safety.

The synthetic rubber binder is used in an amount of about 0.1-4.0% by weight, preferably about 1.0-3.0% by weight, based on the total amount of the anode composition. If the synthetic rubber binder is used in an amount of less than about 0.1% by weight, the anode active material will detach from the anode current collector. This makes the anode plate difficult to manufacture and increases the likelihood of poor anode plate formation. On the other hand, if it exceeds 4.0% by weight, the anode is covered with a synthetic rubber binder, so that the internal resistance of the anode increases and the discharge capacity efficiency of the battery decreases.

In one embodiment, the cellulose-based dispersant included in the anode composition is carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose, ethoxy cellulose, or mixtures thereof. To increase solubility in water, the cellulose-based dispersant may be a sodium or ammonium salt of the above substances.

In one example, the cellulose-based dispersant is used in an amount of about 0.1-4.0 wt%, preferably about 1.0-3.0 wt%, based on the total amount of the anode composition. If the cellulose-based dispersant is used in an amount of less than about 0.1% by weight, the viscosity of the anode composition will be very low, making spreading difficult. On the other hand, if it exceeds 4.0% by weight, the viscosity of the anode composition increases, and the suspension of the anode active material is not suitable as a coating material. In order to eliminate this problem, it is necessary to reduce the amount of anode active material used. However, reducing the amount of anode active material can impair anode characteristics.

In order to produce high-capacity lithium batteries, the amount of active material per unit weight or volume should be as high as possible. In one embodiment of the invention, the addition of a water-soluble anionic polyelectrolyte to the anode composition increases the dispersibility of the anode composition (eg, results in greater deposition of active material). The increased amount of active material in the anode composition, in turn, enhances the performance of the lithium battery.

In order to increase the adhesion of the binder and the dispersibility of the active material, one embodiment of the present invention mixes a synthetic rubber binder with a water-soluble anionic polyelectrolyte and a cellulose-based dispersant. This results in lithium batteries having increased performance.

A method of producing a lithium battery according to an embodiment of the present invention will now be described in detail.

First, the cathode plate was prepared according to the usual method for producing lithium batteries. For this, the cathode active material and the binder are dissolved in a solvent. A plasticizer or a conductive material is further added to the resulting mixture to prepare a cathode composition. The aluminum foil was then wrapped with the cathode composition and dried to produce a cathode plate. The cathode active material can be one or more materials selected from the group consisting of lithium metal composite oxide, elemental sulfur, uranite with Li ₂ S _n (n≥1), organic sulfur, and (C ₂ S _x ) _y where x is 2.5-20 and y≥2.

The anode plate according to the present invention was prepared by the method shown in Example 1, described below.

The preparation method of the electrolyte used in the preparation process of the present invention will now be explained.

The lithium salt contained in the electrolyte used herein is not particularly limited as long as it can dissociate lithium ions in an organic solvent. For example, the lithium salt may be at least one lithium salt selected from lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), and lithium ditrifluoromethanesulfonamide (LiN(CF ₃ SO ₂ ) ₂ ). In one embodiment, the lithium salt is present at a concentration of about 0.5-2.0M. If the concentration of the lithium salt exceeds this given range, the ion conductivity will be insufficient. Organic electrolytes containing the aforementioned inorganic salts allow lithium ions to move between the cathode and anode.

The organic solvent contained in the electrolyte used in the embodiment of the present invention described herein may be one or more selected from the group consisting of polyglyme compounds, dioxolane compounds, carbonate compounds, 2 -Fluorobenzene, 3-fluorobenzene, 4-fluorobenzene, dimethoxyethane, and diethoxyethane.

The polyglyme compound can be one or more selected from following: bis(ethylene glycol) dimethyl ether, bis(ethylene glycol) diethyl ether, tris(ethylene glycol) dimethyl ether, tri(ethylene glycol) dimethyl ether, Ethylene glycol) diethyl ether.

The dioxolane compound may be one or more selected from the group consisting of 1,3-dioxolane, 4,5-diethyl-dioxolane, 4,5-dimethyl dioxolane, 4-methyl-1,3-dioxolane, and 4-ethyl-1,3-dioxolane.

The carbonate compound may be one or more selected from the group consisting of methylene carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, gamma-butyrolactone, dimethyl carbonate esters, ethyl methyl carbonate, diethyl carbonate, and vinylene carbonate.

In one embodiment, the organic solvent is a mixture of ethylene carbonate (EC), ethylmethyl carbonate (EMC), propylene carbonate (PC) and fluorobenzene (FB); or diglyme (DGM ), a mixture of dimethoxyethane (DME) and 1,3-dioxolane (DOX).

The amount of the organic solvent can be the conventional amount used in lithium batteries.

The lithium battery according to the present invention can be produced by any common method known to those skilled in the art, as long as the cathode plate, anode plate and electrolyte are produced as described above.

For example, lithium batteries can be produced according to the following non-limiting three methods. Other methods can also be used. However, three illustrative methods will be presented. In one method, an electrode assembly comprising an anode, a separator, and a cathode is loaded into a battery case, followed by the addition of the electrolyte prepared above. In another method, the polymer resin used for matrix formation is mixed with the electrolyte of the present invention to form a polyelectrolyte composition, and the polyelectrolyte composition is coated on an electrode or a separator to form an electrode assembly, and then the electrode assembly is Packed into the battery box for the production of lithium batteries. In another method, a prepolymer or polymerized monomer of a polymer resin is used for matrix formation, and a polyelectrolyte composition containing the prepolymer or polymerized monomer and the electrolyte of the present invention is coated on an electrode or a separator , to form an electrode device, and then the electrode device is loaded into a battery box, and then the battery box is heated or irradiated with actinic rays, so that the prepolymer or polymerized monomer is polymerized, and a lithium battery is produced.

In general, there is no particular limitation on the separator used in the above method as long as it can be used for lithium batteries. However, in one embodiment, a separator with low resistance to movement of electrolytic ions and good ability to retain electrolyte is used. In another embodiment, a material made of glass fiber, polyester, Teflon, polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), PE/PP, PE/PP/PE, Non-woven or fabric separators made of PP/PE/PP or their blends. Alternatively, the separator may be a polyethylene and/or polypropylene porous film, which hardly reacts with organic solvents and thus is safer.

The polymer resin used for matrix formation in the above method is not particularly limited. Any binder material used for electrode plates can be used, such as polyvinylidene fluoride/hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, or mixtures thereof.

The polymer resin for matrix formation may also contain fillers such as silica, kaolin and alumina to increase the mechanical strength of the polyelectrolyte. The polymer resin used for matrix formation may also contain a plasticizer.

Herein, there is no particular limitation on the type of lithium battery containing the electrolyte. For example, primary batteries, secondary batteries and lithium-sulfur batteries can be used.

Herein, there is no particular limitation on the shape of the lithium battery containing the electrolyte produced according to the present invention. For example, prismatic lithium batteries and cylindrical lithium batteries can be used.

The present invention will be described more specifically below using examples and comparative examples. However, the following examples are for illustration only and do not limit the present invention.

Example 1

Add 97% by weight of natural graphite, 1.0% by weight of carboxymethylcellulose (CMC), 1.0% by weight of styrene butadiene rubber (SBR) and 1.0% by weight of poly(methacrylic acid) (Aldrich) in water , and milled with ceramic balls for about 10 hours. The mixture was spread on the copper foil with a 300 μm spatula, and dried in an oven at about 90° C. for about 10 hours to obtain an anode plate. The anode plate was rolled and cut into a predetermined size to obtain an anode plate sample with a thickness of 120 μm.

Example 2

An anode plate sample was prepared in the same manner as in Example 1 except adding 97% by weight of natural graphite, 1.0% by weight of CMC, 1.0% by weight of SBR and 1.0% by weight of poly(acrylic acid) (Aldrich) in water.

Example 3

Except adding 95% by weight of natural graphite, 2.0% by weight of CMC, 2.0% by weight of SBR and 1.0% by weight of poly(methacrylic acid) (Aldrich) in water, the anode plate samples were prepared in the same manner as in Example 1 .

Example 4

Prepared in the same manner as in Example 1, except adding 96% by weight of natural graphite, 1.5% by weight of CMC, 1.0% by weight of SBR, 0.9% by weight of citrate and 0.6% by weight of tartaric acid (Aldrich) in water Anode plate samples.

Example 5

Except adding 97% by weight of natural graphite, 1.0% by weight of CMC, 1.0% by weight of SBR and 1.0% by weight of poly(acrylic acid sodium salt) (Aldrich) in water, the anode plate samples were prepared in the same manner as in Example 1 .

Example 6

In addition to adding 97% by weight of natural graphite, 1.0% by weight of CMC, 1.0% by weight of methyl methacrylate butadiene rubber and 1.0% by weight of poly(methacrylic acid) (Aldrich) in water, the same as in Example 1 Prepare the anode plate sample in the same way.

Comparative Example 1

An anode plate sample was prepared in the same manner as in Example 1, except that 97% by weight of natural graphite, 1.5% by weight of CMC, and 1.5% by weight of SBR were added to water.

Comparative Example 2

An anode plate sample was prepared in the same manner as in Example 1, except that 98% by weight of natural graphite, 1.0% by weight of CMC, and 1.0% by weight of SBR were added to water.

Preparation 1: Lithium battery

96% by weight of LiCoO ₂ , 2% by weight of poly(vinylidene fluoride) (PVDF) as a binder, and 2% by weight of carbon black (product name: Supper-P) as a conductive agent were mixed together , and 100 ml of N-methylpyrrolidone (NMP) was added thereto. The resulting mixture was milled with ceramic balls in a 200 ml plastic bottle for about 10 hours, spread the mixture onto a 15 μm thick aluminum foil with a 250 μm spatula, and dried in an oven at about 110° C. for about 12 hours to completely evaporate the NMP. Then, the obtained cathode plate was rolled and cut into a predetermined size to obtain a cathode plate sample having a thickness of 95 μm.

A polyethylene/polypropylene porous membrane (Celgard Inc.: product number #: 2300) having a thickness of 20 μm was used as the separator.

A porous membrane was put between the cathode plate samples and each of the anode plate samples according to Examples 1-6 and Comparative Examples 1 and 2, and spirally wound to obtain a jelly-roll structured battery device. Subsequently, the battery device was packed into a cylindrical battery case and a nonaqueous electrolyte was injected into the cylindrical battery case and then sealed to obtain a lithium secondary battery of 1,800 mAh class.

Meanwhile, 5.3 g of ethylene carbonate (EC), ethylmethyl carbonate (EMC), propylene carbonate (PC) and fluorobenzene (FB) containing 1.1M LiPF ₆ (EC/EMC/PC/FB=30 /55/5/10, volume ratio) mixed organic solvent was used as anhydrous electrolyte.

Evaluation 1: Discharge capacity

The discharge capacity of the lithium battery obtained according to Preparation 1 was evaluated with a current of 0.2 Coulomb (C) at -10°C, and the results are shown in FIG. 1 . It can be seen from FIG. 1 that the lithium battery using the anode plate sample of Example 1 exhibits good capacity characteristics at low temperatures. This indicates that the electrical properties of the anode plate are enhanced by the dispersion enhancement of polymethacrylate, which was used as the water-soluble anionic polyelectrolyte in Example 1. In FIGS. 1 and 2, "E" denotes an example and "CE" denotes a comparative example.

Evaluation 2: Adhesion

To evaluate adhesion, a stainless steel rod (4 mm in diameter) was placed vertically on the anode plate samples of Examples 1-6 and Comparative Examples 1 and 2, and the anode samples were scraped with a rod of varying vertical gravity. The vertical gravitational force was measured when the coated film was peeled from the copper foil, and the peel force results for the coated film are given in Table 1 below.

Table 1 sample Adhesion (gf/mm) Example 1 0.9014 Example 2 0.9073 Example 3 0.9253 Example 4 0.9007 Example 5 0.9373 Example 6 0.9168 Comparative Example 1 0.5207 Comparative Example 2 0.5138

Evaluation 3: Life cycle characteristics

The life cycle characteristics of the lithium secondary battery obtained according to Preparation 1 were evaluated, and the results are shown in FIG. 2 . Figure 2 shows the change in discharge capacity of a lithium battery with a standard 1,800mAh discharge capacity during 200 cycles of charging and discharging at a rate of 1 coulomb. As can be seen from Figure 2, the lithium storage battery using the anode plate samples of Examples 1-3 still maintains a discharge capacity of about 1,620mAh or higher after 200 cycles, which is the same as that using the anode plates of Comparative Examples 1 and 2 Compared with the lithium storage battery of the sample, it has an excellent discharge capacity maintenance rate, that is, a life cycle.

The results are given in Table 2 below. Table 2 shows the discharge capacity of the lithium secondary battery obtained according to Preparation 1 with a standard discharge capacity of 1,800 mAh after 200 cycles of charging and discharging at a rate of 1 coulomb, and the percentage of discharge capacity relative to the standard discharge capacity.

Table 2 sample Discharge capacity after 200 cycles (mAh) Discharge capacity % to standard capacity (1,800mAh) after 200 cycles Example 1 1,620 90.0 Example 2 1,630 90.6 Example 3 1,648 91.6 Comparative Example 1 1,471 81.7 Comparative Example 2 1,409 78.3

It can be seen from Table 2 that the lithium batteries using the anode plate samples of Examples 1-3 showed a significantly improved life cycle after 200 cycles compared to the lithium batteries using the anode plate samples of Comparative Examples 1 and 2 characteristic. As can be seen from the above results, the anode composition containing the water-soluble cationic polyelectrolyte has increased adhesion to the substrate, as shown in Table 1 above, which improves the life cycle and other characteristics of the lithium battery.

As apparent from the above description, the lithium battery anode composition according to the present invention contains a water-soluble anionic polyelectrolyte, a synthetic rubber binder, and a cellulose-based dispersant to enhance the dispersibility of the suspension and support the anode plate. of adhesion. This avoids anode plate detachment and internal short circuits due to increased internal battery resistance and decreased anode plate adhesion during repeated charge/discharge cycles, resulting in a long life cycle for lithium batteries. Furthermore, the anode composition of the present invention ensures an increased amount of anodically active material within the anode. The high dispersibility of the anode composition suspension of the invention also ensures good battery capacity characteristics at low temperatures.

For example, the lithium battery of the present invention uses an aqueous anode composition containing water which is harmless to the human body as a solvent. Therefore, it is not necessary to recover the solvent and environmental pollution is reduced. In addition, the lithium battery of the present invention can be effectively used as a power source for portable electronic devices such as cellular phones, PDAs, and notebook computers as well as conventional electronic devices.

Although the invention has been described in detail using specific embodiments thereof, it will be understood that changes in form and details may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the following claims. Variety.

Claims (20)

1. anode composition that is used for lithium battery, this anode composition contains:

Active material of positive electrode;

Synthetic rubber binder:

Based on cellulosic dispersant; With

Water-soluble anionic polymerization electrolyte.

2. anode composition as claimed in claim 1, wherein the consumption of active material of positive electrode is 90-99 weight %, the consumption of synthetic rubber binder is 0.1-4.0 weight %, consumption based on cellulosic dispersant is 0.1-4.0 weight %, and the electrolytical consumption of water-soluble anionic polymerization is 0.1-4.0 weight %.

3. anode composition as claimed in claim 1, wherein water-soluble anionic polymerization electrolyte is selected from citric acid, tartaric acid, butanedioic acid, poly-(methyl) acrylic acid, their salt and their mixture.

4. anode composition as claimed in claim 1, wherein water-soluble anionic polymerization electrolyte is selected from sodium salt and ammonium salt.

5. anode composition as claimed in claim 1, wherein synthetic rubber binder is selected from styrene butadiene ribber, the nitrile butadiene rubber, (methyl) methyl acrylate butadiene rubber, chloroprene rubber, carboxy-modified styrene butadiene ribber, the organo-siloxanes polymer of modification and their mixture.

6. anode composition as claimed in claim 1 wherein is selected from carboxymethyl cellulose based on cellulosic dispersant, carboxyethyl cellulose, aminoethyl cellulose, ethoxy cellulose and their mixture.

7. anode composition as claimed in claim 6 wherein is selected from sodium salt and ammonium salt based on cellulosic dispersant.

8. anode composition as claimed in claim 1, wherein active material of positive electrode is selected from the carbonaceous material of native graphite, Delanium, coke and carbon fiber.

9. the anode of a lithium battery, this anode contains:

Contain active material of positive electrode, synthetic rubber binder, based on cellulosic dispersant and the water-soluble electrolytical anode composition of anionic polymerization, this water-soluble anionic polymerization electrolyte is selected from citric acid, tartaric acid, butanedioic acid, poly-(methyl) acrylic acid, their salt and their mixture.

10. use the lithium battery of the anode of claim 9.

11. anode composition as claimed in claim 1, wherein active material of positive electrode is the compound that is selected from Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb and Ti.

12. anode composition as claimed in claim 1, wherein active material of positive electrode is to contain the lithium nitride.

13. anode composition as claimed in claim 1, wherein active material of positive electrode is the complex compound that is selected from Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb and Ti.

14. contain the lithium battery of anode, this anode contains:

Contain active material of positive electrode, synthetic rubber binder, based on cellulosic dispersant and the water-soluble electrolytical anode composition of anionic polymerization,

Wherein this water-soluble anionic polymerization electrolyte is selected from following group one group:

First group is citric acid, tartaric acid, butanedioic acid, poly-(methyl) acrylic acid, their salt and their mixture; With

Second group is sodium salt and ammonium salt.

15. lithium battery as claim 14, wherein the consumption of active material of positive electrode is 90-99 weight %, the consumption of synthetic rubber binder is 0.1-4.0 weight %, consumption based on cellulosic dispersant is 0.1-4.0 weight %, and the electrolytical consumption of water-soluble anionic polymerization is 0.1-4.0 weight %.

16. lithium battery as claim 14, wherein synthetic rubber binder is selected from styrene butadiene ribber, the nitrile butadiene rubber, (methyl) methyl acrylate butadiene rubber, chloroprene rubber, carboxy-modified styrene butadiene ribber, the organo-siloxanes polymer of modification and their mixture.

17. as the lithium battery of claim 14, wherein be selected from carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose, oxygen ethyl cellulose and their mixture based on cellulosic dispersant.

18., wherein be selected from sodium salt and ammonium salt based on cellulosic dispersant as the lithium battery of claim 14.

19. as the lithium battery of claim 14, wherein active material of positive electrode is selected from the carbonaceous material of native graphite, Delanium, coke and carbon fiber.

20. as the lithium battery of claim 14, wherein active material of positive electrode is the carbonaceous material that contains the lithium nitride.

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